1. Field of the Invention
The present invention relates in general to a charging system for a battery. In particular the present invention relates a remote charging system for electric and hybrid electric vehicles.
2. Prior Art
There have been numerous attempts and initiatives established for next generation land based vehicles. Some programs have set goals for vehicle mileage of 80 miles/gal and greatly reduced vehicle emissions based on today's standards. Federal and local governments have placed limits on emissions and well as standards for fuel consumption. Even with regenerative braking energy, a hybrid electric/internal combustion vehicle will be pressed to meet these goals. A wireless method of transmitting electrical energy to vehicles would help to overcome present obstacles.
One of the major causes of smog today is the use of city buses for public transportation. Diesel and gasoline driven buses spew out tons of pollutants daily. Utilization of buses powered by electricity would eliminate this source of pollution from our cities. To date, the most reliable electric source has been overhead tethered line or on-ground tracks. But these greatly reduce the convenience of route changes and are at the mercy of small traffic pattern changes which can cause traffic tie-ups. The ideal electric bus would have a completely mobile energy source, such as a battery pack. But the limited range of a battery powered vehicle has diminished its use to only specific cases.
In large cities a single battery pack, consisting of several standard 12- or 24- volt batteries, provides for driving an all-electric bus one or two route cycles before the vehicle must be pulled out of service for either an expensive battery pack replacement to allow the battery unit time to be recharged while the vehicle is put back on the road immediately with a fresh battery pack; or taken completely out of commission while the battery unit is being charged on the vehicle. Recharging the battery pack can be a four-or five-hour process. Therefore an all-electric, completely mobile city bus service is cumbersome to run and maintain, difficult to meet schedules and expensive to operate.
Originally wireless power transmission system was proposed to augment the existing system of electrical conductors that are used to move large quantities of electrical power over long distances. In the mid-1960s a system was proposed to convert large quantities of solar energy into an energy beam that could be transmitted from outer space to the surface of the earth through satellite transmissions. Once on earth the energy beam would be converted back to a usable voltage form that would be pumped into the existing electrical energy distribution grid. Several transmission frequencies of the energy spectrum have been considered to minimize the energy loss from the beam as it travels through the atmosphere, such as radio frequency (RF), laser, and optical frequency (OF). For the RF energy beam, atmospheric attenuation is a minimum up to 4 Ghz, even during a heavy rainstorm. Other windows of transmission exist at 35 Ghz and 94 Ghz. Systems designed to operate at these relatively high frequencies have the added advantage of operating at smaller apertures wherein the transmitting antenna and the receiving antenna can be smaller. Such systems have been considered for transmission distances of kilometers in conjunction with satellites in low earth orbit or geosynchronous orbit, transmitting to the surface of the earth. Transmitting from space to the surface of the earth also eliminates laser beams from traveling long distances in the earth's atmosphere.
A wireless remote system capable of transmitting at distances of 200 to 500 meters is needed. With these relatively short distances, while taking into account additional power requirements for attenuation in the earth's atmosphere, many more RF bands become available, as well as the viability of transmitting energy via laser beam. Laser energy beam technology also has the advantage of having relatively small transmitting and receiving antennae. What is needed is a remote charger system for an electric vehicle which replaces the current internal combustion engine, reduces emissions problems, and which enables the electric vehicles to have full mobility. There is also a need for a vehicle remote charge network which can be installed with minimum impact on existing streets and is expandable from public transportation vehicles to private all-electric vehicles.